Electromagnet horn



Nov. 12, 1935. R. M. CRlTCHFlELD ET AL 2,020,768

I ELECTROMAGNET HORN Filed May 31, 1930 2 Sheets-Sheet 1 Zlwmntoz:

c755 WH/ TE ROBERT/W. C/P/TCHF/ELD R. M. CRITCHFIELD ET AL 2,020,768

ELECTROMAGNET HORN Nov. 12, 1935.

Filed May 31, 1930 -2 Sheets-Sheet 2 JbE WHITE ROBERT M CR/TCHF/EL 0Patented Nov. 12, 1935 UNITED STATES PATENT OFFICE ELECTROMAGNET HORNporation of Delaware Application May 31, 1930, Serial No. 458,610

15 Claims.

This invention relates to sound signal devices, and particularly to thevibratory type.

One of the objects of the invention is to provide a sound signal of theclass described that will manifest in a clarity of tone. v

A further object of the invention is to provid adequate means ofadjustment under various conditions of operation.

A further object of the invention is to provide means of varying thepitch of the sound product.

A further object of the invention is to improve generally sound signaldevices of the class described.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred embodiment of one form of the presentinvention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal sectional View of a sound signal deviceillustrating the preferred form, being a sectional view substantially asindicated by the line and arrows of Fig. 3.

Fig. 2 is a longitudinal sectional View similar to Fig. 1, butillustrating a modified form of the instant invention, and with thesection through the magnet motor being taken substantially at rightangles to that illustrated in Fig. 1, being substantially that indicatedby the line and arrows 22 of Fig. 1 or 3.

Fig. 3 is a rear elevation of a power plant with a section through thehousing substantially as indicated by the line and arrows 3-3 of Fig. 1.

Fig. 4 is a plan View of the modified form of mouth piece substantiallyas indicated by the line and arrows 44 of Fig. 2. v

Fig. 5 is a transverse sectional View of the same substantially asindicated by the line and arrows 5-5 of Fig. 2.

With particular reference to the drawings, 2|] indicates a mountingplate of a sound signal device to which is clamped a collar 2| by meansof screw devices 22 that operate to rigidly secure a vibratory diaphragm23 at its peripheral edge 24. The mounting plate 20 has provision forsupporting a field frame 25 by screw studs 26 secured therein and inclamping engagement with brackets 21 and 28 by means of nuts 29 and 30.The

brackets 27 and 28 are secured to the field frame 25 in any desirablemanner as is well known to those experienced in the art, and operates toadjustably support the field frame with respect to the foundation plate20.

In proper magnetizable relation with the field frame 25, a field coil 35is secured by clips 36 in the usual manner, and the windings of the coilhave appropriate connection with the circuit breaker mechanism 31supported by an appropriate lug 38 struck up from the foundation plate 520. The circuit breaker mechanism includes a fixed contact support 39providing a contact 40 optionally engageable with and separate from amovable contact 4| carried by a leaf spring conductor 42, the end ofsaid spring being disposed in the path of an actuating nut 42a carriedby an armature rod 43 reciprocable through the central aperture 44 ofthe field frame 25. In the preferred form the magnet frame 25 carries abushing or sleeve 45 through which the armature rod slides in itsmovement to the central aperture 44. Reciprocable movement of thearmature rod 43 is accomplished by providing it with an armature 46against which is disposed a spacer 41, and thence making engagement withthe diaphragm 23 by aid of a pair of clamping washers 48 and 49 oneither side of the diaphragm and secured thereto by the lock washer andnut device 50. To establish better operation and make the magnet motormore responsive to electrical impulses impressed thereon, a condenser 5|is provided with appropriate leads 52 and 53 making connection with thecircuit breaker mechanism and is embraced by a clip 54 secured to thefoundation plate 20 as by a screw 55. In Fig. 2, certain modificationsof structure are illustrated, but in main the structure is essentiallythe same, in that the foundation plate 20 supports a field frame 25operable upon an armature 46 carried by an armature rod 43 that actuatesthe circuit breaker mechanism 31 as does the structure of Fig. 1. In theform illustrated in Fig. 2, the armature rod 43 is supported at thecontact breaker mechanism by a short spring member 56 secured to thebracket 38 and engaging the rod 43 through the agency of a clip 51 andnut 58. Since this structure is old in itself and is illustrated incopending applications, it is deemed that further illustrationisunnecessary. However, when a proper source of ourrent and a switch areconnected with terminal members 60 and GI, energization of the fieldcoil 35 will operate to draw the armature 46 against the field frame 25,and in doing so the engaging nut 42 will move the contact 4| away fromthe contact 4|], whereupon the field coil will be deenergized. Uponenergization of the magnet mo.- tor the diaphragm 23 will be moved withthe armature 46, and when the field coil is deenergized by breaking ofthe circuit through contacts 40 and 4| the diaphragm 23 will movebackward along with the armature 46.

In the illustrated embodiment the sound signal device is provided with atrumpet or projector 65 that has connection with a mouth piece (itsupported by the collar 2!, in close contiguous relation with thevibratory diaphragm 23. In the preferred form illustrated, the mouthpiece 66 manifests in a Venturi portion 61 that has uninterruptedcommunication with the toe 68 of theprojector. From the venturi 6! themouth piece 66 rapidly flares outwardly to present the sharpened lip 69disposed in operable relation with the diaphragm 23. In practice it hasbeen found desirable to form the mouth piece 66 as illustrated, with thecylindrical portion 10 threaded to cooperate with a central aperture Hof the collar 2!, and a clamping nut 72 of desired form may be threadedupon the cylindrical extension fill and run up against the collarZl soas t hold the mouth piece fifi in the desired position. Means are thusalso provided for supporting the trumpet 65 in definite relation withrespect to the lip 69 oi the mouth piece so that an air column ofdefinite length can be assured. The union of the trumpet 65 with themouth piece is assured by securing to the toe 68 ofthe trumpet, a collar13 about which is disposed a clamping nut 14 that operates to secure thetrumpet firmly to the mouth piece 56 by threading the same upon thecylindrical extension Hl.

In the form illustrated in Fig. 2, that illustrating the modification, acollar member Zia is similarly secured to the foundation plate 26 by thescrew devices 22' and operates to rigidly clamp adiaphragm 230. at itsperiphery as in the preferred form. The diaphragm ZShas connection withthe armature rod 43 by the clamping discs 48 and 49 and the nut lockiflas in-the preferred form. While the diaphragm 23a, of Fig. 2 is flat ascompared with the corrugated dia-. phragm 23 of Fig. 1, its operation isessentially the same, in that upon operation; of the magnet motor itfunctions to alternately open and stop the air column at the inner endor mouth piece of the trumpet.

The greatest difference-in the; structure of the two forms illustratedis in the form of the mouth piece, and is believed to be clear asillustrated. In the modified form the mouthpiece 66a is considerablygreater in external diameter, but

like the mouthpiece B6 is threadedinto the front of the collar Zia asindicated at Tia. and is secured in'its adjusted position by a clampingnut or ring 12a, Here, the lip 69:; is not as sharply defined as the lip59 of the preferred form, but

of the'collar 21a.

the wall of the mouth piece 66a rapidly diminishes to a venturi We as inthe preferred form, and opens into the toe 68a. of the projector withoutinterruption of the contour as does the preferred form. The terminatingedge of the toe' 68a is flared outwardly into a flange at l5 where it isengaged by a packing nut 76 operating to secure the trumpet to the mouthpiece 61a; by threaded engagement with an aperture ll coaxial with theventuri 61a. .About the aperture Tithe mouth piece 66a is providedwith ahexagon or otherwise angular boss l8 whereby provision is made forturning the same and out In either form the device whether it be'thepreferredform illustrated in Fig. 1 orthe modified form illustrated inFig. 2, the mouth piece rigidly supports the projector and is axiallyad- I, nite length of the air column between the lip of the mouth pieceand the bell of the trumpet is not disturbed, for as the lip movesinwardly so does the bell move inwardly.

In the operation of the magnet motor the diaphragm 23 or 2311, as thecase may be, is pulled away from and allowed to slap back against thelip of the mouth piece in a rapid succession of blows, and this movementoperates to suddenly open and stop the column of air present in thetrumpet. Thus, a tone product of definite timber will be provided, thepitch of which depends mainly upon the length of the air column that isstopped. By joining the venturi of the mouthpiece with the toe of thetrumpet without ma terial interruption of the continuity of surfaceinterference of the sound product is therebysubstantially eliminated,and the tone product that results is substantially a true air tone.

While the form of embodiment of the present invention as hereindisclosed, constitutes a pre ferred form, it is to be understood thatother forms might be adopted, all coming within the scope of the claimswhich follow. a

What is claimed is as follows:

l. A sound signal comprising in combination, a motor, a supporting platefor the same, a dished clamping collar secured to the plate, a vibratingdiaphragm actuatable bythe motor and clamped between. the plate andcollar to form an air chamber, with the dished member, a projectorsupported by the collar having a mouth piece within the air chamberclosely continguous to the diaphragm, said mouth piece forming an inletand outlet passage for said chamber, and means for varying the relativepositionof the mouth piece with respect to said diaphragm so that themouthpiece will be engaged by the diaphragm as the diaphragm is flexedtoward the mouth piece.

2. A sound signal comprising in combination, a motor, a supporting platefor the same, a dished clamping collar secured to the plate, a vibratingdiaphragm clamped between the plate and collar to. form an air chamber,with the dished member, a projector supported by the collar having amouth piece projecting within the air chamber to form a fulcrum closelycontiguous to the diaphragm, said mouth piece providing a'sole inlet andoutlet passage for said chamber, said motor being operably connectedwith the diaphragm to alternately move the diaphragm from and to contactwith the fulcrum,

and thereby adapted to open and stop the mouth piece at the lipsthereof.

' 3. 'A sound signal comprising in combination, 8

ing the sole passage to said chamber, said motor a operable to move thediaphragm alternately into and out of contact with the fulcrum, andmeans for varying the relative position of the fulcrum With respect tothe diaphragm without varying the length of the air column of saidprojector.

' 4. A sound signal comprising in combination; a motor; a supportingplate for same; a cupshaped clamping collar secured to said plate; avibrating diaphragm clamped between the plate and collar to form an airchamber; a projector supported by said collar having a mouth piececlosely contiguous to the diaphragm, said mouth piece forming an airinlet and outlet passage for said chamber, said motor having a positiveconnection with said diaphragm for vibrating the diaphragm alternatelyto move from and to contact with the mouth piece as a fulcrum wherebyair is alternately drawn into and expelled from the chamber.

5. A sound signal comprising in combination; a motor; a supporting platefor same; a cupshaped member secured to said plate; a diaphragm clampedbetween the cup-shaped memher and plate to form a closed chamber, saiddiaphragm having a positive connection with said motor, a trumpetprovided with a mouth piece to provide the sole opening to said chamber,means supporting the mouth piece in contiguous relation with thediaphragm so as to provide an annular fulcrum for the diaphragm, saidmotor actuating the diaphragm from and to contact with the fulcrum,whereby the air column through said mouth piece will be alternatelyopened and closed by the diaphragm and the major portion of diaphragmactuation will be confined to that portion within the bounds of theannular fulcrum.

6. In a sound signal, a casing comprising a cup shaped member, adiaphragm mounted on the rim of the cup shaped member, a mouth piecesupported concentrically of the cup shaped memher and extending into thecasing with its edges contacting the diaphragm so as to close thecasing, and means for vibrating the diaphragm to move the diaphragmalternately from and to contact with the mouth piece whereby air isalternately drawn into and expelled from the casing.

'7. In a sound signal the combination comprising, a casing including acup shaped member, a diaphragm mounted on the rim of the cup shapedmember, a mouth piece supported concentrically of the cup shaped memberand providing an annular fulcrum contacting the diaphragm so as to closethe casing, and means including a vibration motor for vibrating thediaphragm to move the diaphragm alternately from and to contact with thefulcrum whereby the diaphragm is arrested at the fulcrum but the centralportion of the diaphragm is permitted to continue its movement to apoint substantially within the mouth piece.

8. In a sound signal the combination comprising, a casing including acup shaped member, a diaphragm mounted on the rim of the cup shapedmember, a mouth piece supported concentrically of the cup shaped memberand extending into the casing with its edges contacting the diaphragm soas to provide an annular fulcrum for the same, and a motor for vibratingthe diaphragm alternately from and to contact with the mouth piece, andfor continuing movement of the central portion of the diaphragm to apoint within the mouth piece after the diaphragm has engaged the annularfulcrum whereby an increased volume of air is moved through the mouthpiece.

9. In a sounding signal of the class described the combinationcomprising, a chambered member opening into a trumpet and providing anoffset rim, a diaphragm mounted on the rim of the chambered memberproviding a closed wall therefor, a mouth piece projecting within thechambered member and having a lip normally engaging the diaphragm toclose off the chambered member, and a motor for vibrating the diaphragmfrom and to contact with the lip and for forcing a portion of thediaphragm within the mouth piece whereby air is alternately drawn intoand expelled from the chambered member.

10. In a sounding signal the combination comprising, a trumpet, achambered member provided with a rim, a concentrically corrugateddiaphragm mounted on the rim of the chambered member, a mouth piecewithin the chambered member communicating with the trumpet and having alip concentric with the rim and engaging the diaphragm along thejuncture of two successive corrugations, and a motor for actuating thediaphragm from and to contact with the lip whereby the diaphragm when itapproaches the lip will have an annular portion thereof arrested at thelip, and that portion within the boundary of the lip will move to aposition substantially within the mouth piece,

11. In a sounding signal the combination comprising, a trumpet, achambered member provided with a rim, a concentrically corrugateddiaphragm mounted on the rim of the chambered member, a mouth piececommunicating with the trumpet and having a lip within the chamberedmember intermediate the rim and diaphragm center, and a motor foroscillating the diaphragm from and to contact with the lip so that thediaphragm will move as a whole against the lip, and so that the centralportion of the diaphragm within the lip will continue its movementtoward the mouth piece.

12. In a sounding signal the combination comprising, a trumpet, achambered member provided with a rim, a concentrically corrugateddiaphragm mounted on the rim of the chambered member, a mouth piecewithin the chambered member providing an annular fulcrum intermediatethe rim and diaphragm center so as to engage the diaphragm along thejuncture of two successive corrugations, and a motor for actuating thediaphragm from and to contact with the fulcrum, and after moving thediaphragm into contact with the fulcrum to substantially rock the sameover the annular fulcrum whereby the volume of air movement through thetrumpet and mouth piece is increased.

13. In a sounding signal the combination comprising, a trumpet, achambered member provided with a rim, a concentrically corrugateddiaphragm mounted on the rim of the chambered member, means providing anannular fulcrum for the diaphragm intermediate the rim and diaphragmcenter and so as to engage the diaphragm at the juncture of twosuccessive corrugations, and a motor to actuate the diaphragm from andto engagement with the said means and to bend the central portion of thediaphragm relative to the outer portion upon engagement with the fulcrumso as to increase the mass of air movement through the trumpet.

14. A sounding signal comprising, a housing, a diaphragm havingconcentric corrugations mounted in the housing and adapted foroscillation, a motor mechanism connectedto said diaphragm for flexingthe same, a throat member supported by the housing to provide an openingtherefor, and having a part disposed in engageable relation with thediaphragm along the juncture of two successive corrugations, said motorwhen flexing the diaphragm on thercompression stroke driving thediaphragm against the end of the throat member, and thence pushing thecentral portion of the diaphragm bounded by the throat engagement towarda point Within and at the axis of the throat member, whereby membersu'pp'orted'by the housing to provide an opening therefor, and having apart disposed in engageable relation with the diaphragm, said motor whenflexing the diaphragm on thelcoitnpression stroke causing the diaphragmto move as a whole against the end of the throat member, andthus causingthe part of the diaphragm within the boundary of the throat member tocontinue its movement toward a point within the throat member while thatpart of the diaphragm without the boundary of the throat member issubstantially arrested or caused to reverse its movement so that thediaphragm is flexed radially over the end of the throat member as afulcrum.

JOE WHITE.

ROBERT M. CRITCHFIELD;

